Multirange wave trap



June 6, 1950 w. v. ARNETT MULTIRANGE WAVE TRAP Filed July 8, 1944 2oINSULATION INVENTOR WILLIAM V. ARNETT. BY 'w ATTORN EY l atented june 6195i) MULTIRANGE WAVE TRAP William v. Arnett, Audubon, N. J.-, assignor0- Radio Corporation of America, a corporation of Delaware ApplicationJuly 8, 1944, Serial No. 544,105

6 Claims.

This invention relates to a new and useful multi-range wave trap, whichis particularly adapted to ultra high frequency use.

An object of this invention is to provide a small simple efiicient andfreq-.zency stable wave trap for ultra high frequency operation.

A feature of this invention is the novel arrangement of a cylindricalinsulating tube, a support member, a variable air condenser and aninductance coil wound on the outside of the insulating tube.

Briefly the device of this invention comprises a movable electrode ofthe plunger air dielectric trimmer type condenser which is arranged tomove inside a fixed metal tube. The metal tube is located within theinsulating tube which is secured to a support member. Connected to anend of the fixed tube of the variable condenser electrode is aninductance coil which is positioned around the cylindrical insulatingtube. The other end of the inductance coil connects to an insulatedterminal mounted on a support member. The movable condenser electrode isin capacitive relationship with the fixed condenser electrode to varythe impedence thereof.

Although wave traps are old in the art, they do not all provideefficient and frequency stable operation when used in ultra highfrequency circuits.

This invention is particularly adapted to provide an efficient wavetrap, which will be stable at the ultra high frequencies, regardless oftemperature changes. The wave trap of this invention may be employed totune a radio transmitter circuit over a considerably wide frequencyrange and is simple in construction and rugged in operation. The deviceof this invention may be employed equally as well in a receiving circuitas in a transmitting circuit.

This invention will best be understood by referring to the accompanyingdrawing, in which:

Fig. 1 isa circuit diagram of the wave trap of this invention;

Fig. 2 is an end view of the wave trap of this invention;

Fig. 3 is a side elevation of Fig. 2; and,

Fig. 4 is a longitudinal section of Fig. 3.

Referring now in detail to the circuit diagram shown by Fig. 1 of thedrawing, the inductance coil l is shown as being connected at one end toa fixed electrode 2 of an air variable condenser. The condenser variableelectrode 3 includes a metallic rod which is arranged to telescopewithin the electrode 2. The circuit arrangement of the inductance andcondenser electrodes is such as to provide either a parallel tunedcircuit or series tuned circuit arrangement.

The structural details of the Wave trap of this invention is shown indetail'by Figs. 2, 3 and 4 of the drawing. They comprise a metallicbracket member 4. which is bent at right angles at 5, to

telescope within tube '2. 'portion is peaned over as shown to preventprovide a foot or mounting portion. A non-circu lar aperture 4A isprovided to retain the wave trap unit. The mounting portion of bracket 4is provided with tapped holes 6 for securing the same to any suitablechassis or other electrical structure (not shown). An insulatingterminal board 1 is secured to the bracket member 4 by means of a pairof rivets 8. A single terminal eyelet 9 is fastened to terminal board 1and secures a U- shaped terminal clip l2 thereto. An insulating tube i3is provided with corrugated ends l3A to grip with metal ends I33 andI30, which are moulded on. The metal ends I3B and ISO are moulded in asplit mould of any suitable size and indicated by the dot and dash lines13D. The preferred metal is a solder comprising about Gil percent tinand percent lead. The moulded ends also retain tube 2 and a metallicbushing IT in place, as shown by Fig. 4. Bushing I1 is threaded andsplit at 11A to provide locking means for rod 3 by the tightening of ametal bushing nut or chuck I6. A flattened portion llB on bushing i1prevents the turning of the wave trap unit as it is mounted in thenon-circular aperture 4A, in bracket member 4. In order to provideproper insulation it will be noted that the metallic electrode tube 2does not extend all the way through insulating tube IS. The insulatingtube I3 together with the metallic bushing I! is secured to member 4 bymeans of a threaded nut l4. At a point I 5 the inductance coil I issoldered to the metal end 13C which connects the fixed electrode 2. Theinductance I consists of seven or any desired number of spaced turns ofheavy copper enameled wire which are wound around the insulating tube Itto give the proper inductance. The turns are secured inplace by acoating of any suitable insulating liquid such as styrol. The free endof coil I is soldered to clip l2 at I2A and serves as one terminal ofthe wave trap. The other terminal of the wave trap is that of the rod 3,which in turn is electrically connected to the bracket 4. The impedanceof the device is varied by means of telescoping the metallic rod 3 whichforms the variable condenser electrode within the ceramic tube 13, Anysuitable insulated tool (not shown) may be inserted in hole l9 to varyits capacity. When the proper impedance of the device is obtained therod 3 is locked in position by means of a threaded bushing nut it, whichrotates around the threaded bushing ll.

One end of rod 3 has a stud portion 3A which retains an insulatingwasher 20 of ceramic material. Washer 28 is to prevent a short circuitbetween rod' 3 and tube 2, and is made larger in diameter than rod 3,but of such size as will The end of the stud washer 20 from coming offwhen rod 3 is moved.

In the operation of this device the proper connections are made betweenone end of coil I at terminal clip l2, and the variable electrode 3 atbracket'ill; that is, if it is desired to be a series tuned circuit. Ifa "parallel tun'edbircuit' arrangement is desired, a connecting link it(shown by a dotted line in Fig. 1) is connected between the terminalclip I2 and bracket 4. The incoming terminal connections are made fromclip [2 and the metal tube Zwhen-using link l8 for the parallel tunedcircuit. The proper impedance is obtained by a movement of the variableelectrode 3, which is in capacitive relationship with the fixedelectrode 2.

While I have described a device for carrying my invention into efiect,it will be apparent to 'one"skilled in-the art that 'myinvention is byno 'in'eans' limited'to' the particular device shown and described, butthat many modifications may be made withoutdeparting from'thescope ofthe invention.

What I claim is:

1. A high frequency wave trap comprising a metallic angle-shaped supportbracket, an insulating cylinder having corrugated ends, a helical spacewound inductive coil wound outside of said support bracket andelectrically connected is to the other end of said coil, and a variablecondenser electrode arranged to move within said fixed cylindricalelectrode to var the impedance of said wave trap.

2. A high frequency mu1ti-range wave trap comprising an insulatinghollow cylinder, metallic ends for partly closing said hollow cylinder,a support member for said insulating cylinder, an inductive coil locatedoutside of said insulating cylinder, a 'fixed condenser electrodelocated inside of said insulating cylinder and electrically connected toone end ofsaid coil by one of said metallic ends, the other one of'saidmetallic ends having threaded means located outside of said supportmember, a threadedhollow chuck for said threaded means, and a variablecondenser electrode in the interior of said chuck, said chuck acting'tolock said variable condenser electrodein a desired capacitiverelationship with said first mentioned electrode.

3. A high frequenc wave trap comprising an insulating hollow "cylinder,metallic ends for partly closing said hollow cylinder, a terminalmember, a space wound inductive coil wound outside of said insulatingcylinder, a fixed con denser tubular electrode located within saidinsulating cylinder and electrically connected to one end of said coilby said one of the metallic ends, the other end of'said coil beingelectrically connected to said terminal member by the other one of saidmetallic ends, a variable rod condenser electrode having a smalleroutside diameter than the inside diameter of said fixed condensertubular electrode, and an insulating end sleeve attached to one end ofsaid variable rod condenser electrode so as to'move within the inside ofthe fixed condenser tubular electrode, sothat said variable rodcondenser electrode may sulating move within said fixed tubularelectrode to be in capacitive relationship therewith to vary theimpedance of said 'wave't'ra'p. l

*4. A high frequency wavetrap "comprising a metallic support bracket, aterminal member, an

insulating hollow cylinder having corrugated "said moulded end, saidterminal' member insulatingly secured to said Support bracket and"electrically connected to the other'endof saidicoil,

and a variable condenser electrode "arranged to 'movewithin saidfixedcylin'dri'cal electrode to vary the impedance of said wave trap.

5. A high freq'uencywave trap comprising an insulating hollow cylinder,aniangle-shaped support member, metallic ends for partly closing saidhollow cylinder, a terminal member secured to said support member, aspace wound metallic coil Wound outside of said insulating cylinder, afixed condenser tubular electrodelocated within said insulating cylinderand electrically connected to one end of said coil by one of themetallic ends, the other end ofsaid coil being electrically connected tosaid terminal member, said other one of said metallicends'havingthreaded means located outside said support member, a

threaded hollow chuck for said threaded means and a 'variablecondenserelectrode in the interior of said chuck, said chuck acting to lock saidvariable condenser electrode in a'desired capaci- "tiverelationship'withsaid first mentioned electrode.

'6, A high'frequency wave trap comprising an insulating hollow cylinder,an angle shaped metallic support'member, metallic ends for partly closinsaid hollow cylinder, a terminal member insulatingly secured to saidsupport member, a space wound metallic coil wound outside of saidinsulating cylinder, a fixed condenser tubular electrode located withinsaid insulating cylinder and electrically connected to one end of saidcoil by one of the metallic ends, the other end of said coil beingelectrically connected to said terminal'member, said other one of saidmetallic ends having threaded means located outside said support member,a threaded hollow chuck for said threaded means and a variable rodcondenser electrode positioned in the interior of said fixed tubularelectrode, said threaded hollow chuck acting to lock said variableelectrode in a desired capacitive relationship with said first mentionedelectrode.

WILLIAM V. ARNETT.

REFERENCES CITED The'following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,913,532 Bohner June 13, 19332,014,422 Carter Sept. 17, 1935 2,028,596 Franklin et al. Jan. 21, 19362,209,626 Larki July 30, 1.940 2,422,458 Amy et al June 17, 1947

